XML Paper Specification (XPS) is a paginated document format developed by Microsoft that specifies the content and appearance of an electronic document. Open XML Paper Specification (OpenXPS) is a paginated document format that is based on XPS but which differs in some respects from the format used in XPS. OpenXPS is a standard adopted by the European Computer Manufacturers Association (ECMA) as ECMA-388. The OpenXPS standard requires conformance to the schema defining the OpenXPS format and the XPS specification requires conformance to the schema defining the XPS format. Due to the differences between the two formats, it may not be possible for XPS and OpenXPS documents to be used interchangeably.